Engines may use various forms of fuel delivery to provide a desired amount of fuel for combustion in each cylinder. One type of fuel delivery uses a port injector for each cylinder to deliver fuel to respective cylinders. Still another type of fuel delivery uses a direct injector for each cylinder. Further, differential injection of gasoline and an alcohol (e.g., ethanol), may also be used to further improve engine performance.
One approach to on-board separation of fuel components may use heating to improve separation. For example, as described in U.S. Pat. No. 6,711,893, a mixed fuel may be heated by a heater prior to reaching a fuel separation device such that the overall efficiency of the fuel separation process is increased. Similarly, as described in US 2006/0191727, a mixed fuel may be heated via compression by a fuel pump prior to reaching an ethanol selection permeable membrane such that the overall efficiency of the fuel separation process is increased.
To address potential parasitic losses of such approaches, a method for operating an internal combustion engine with a compression device is provided, the method comprising: compressing a flow of engine intake air via the compression device; directing the flow of engine intake air to a first side of a membrane; directing a mixed fuel including at least a hydrocarbon component and an oxygenated component to an opposite side of the membrane; separating the mixed fuel into a first hydrocarbon-enriched fuel fraction and a second oxygenated-enriched fuel fraction by selectively diffusing at least a portion of the oxygenated-component through the membrane into the flow of engine intake air flowing along the first side of the membrane. The hydrocarbon-enriched fuel fraction may be delivered to the engine and/or to a storage tank, for example.
Thus, by utilizing air that has been heated by a compressor (e.g., a compressor of a turbocharger that is used to increase engine charging), separation may be improved while reducing parasitic losses. For example, even if parasitic heating is used in addition to compression heating, less parasitic heating may be used for a given operating condition. In other words, the heated air received by the separator from the compressor may increase the overall separation rate and efficiency of the separator while reducing heating by other potentially more parasitic approaches. Further, compressor operation may be adjusted based on performance of the separation, for example, such that increased compression heating, and increased boost, may be used when increased separation is requested.
Note that a side of a membrane may refer to one side of a planar membrane, as well as an inside or outside of a tubular membrane, or others, for example. Further, the membrane may be supported on a support structure and/or include additional components.